aiming and deflection... for a newbie

[dr_dave]

Swerve happens sooner with follow shots than with swerve shots, so the CB does not swing out as much, making it appear there is less squirt (which is not the case) or more swerve (which really isn't the case either) ... the swerve just occurs earlier.

What you are saying in this post seems to contradict what you have said in this video, http://billiards.colostate.edu/normal_videos/new/NVB-7.htm

Why do you think there is a contradiction? The point of NV B.7 is to show that the CB's path does not turn after the CB has begun to roll (even with sidespin), assuming the table is level and the cloth is in good condition and clean (and the ball's weight is balanced).

There is both squirt and swerve in that video, and I did correct my aim for them, but they occur in the first few inches of the shot since the speed is so slow. Squirt occurs immediately off the tip, and swerve occurs only while the CB is sliding (not rolling yet). The amount I had to adjust for the combined effects of squirt and swerve was not very much because for the cue, speed, and cue elevation I was using, swerve cancelled most of the squirt (but I did have to adjust a little as predicted by the FHE method for slow, rolling shots).

I hope that makes sense,
Dave

 

[dr_dave]

I hope it doesn't appear that I'm ragging on you (you know I wouldn't do that as I highly respect the great efforts you have put into this wonderful game), but for clarity's sake, I would like to ask one more question.

Roger,

I've never feel ragged-on by you. You ask intelligent questions and it is obvious that you are here to share and learn information and insight.

In post #38 you said, "Squirt does not depend on speed..."

That is most definitely true. Conclusive proof can be found in the articles on the squirt speed effects resource page.

However, in this video, http://billiards.colostate.edu/normal_videos/new/NVB-32.htm I know you are demonstrating the effects of end-mass on squirt, but in the first shot where you show a non-squirt shot by hitting on the vertical center-line, and most likely above the horizontal center-line as well, you hit the ball at a relatively slow speed. But when you go to demonstrate the shots involving squirt, you blast the balls. If squirt does not depend on speed, why do you have to hit them so hard to demonstrate squirt? (I also think you were hitting on the horizontal center-line for maximum effect.)

In NV B.32, soft speed was used on the first shot to help ensure the most accurate hit possible. Fast speed was used on all of the sidespin shots to minimize the effects of swerve. A fast speeds, the CB does not have time to swerve (curve) very much allowing us to see the isolated effects of squirt.

Roger, it seems like you (like many others) use the term "squirt" or "CB deflection" to indicate the net result of both squirt and swerve (AKA "squerve" or "net CB deflection"). I think that is the source of most of the confusion in threads like this. Squirt and swerve are very different effects and they depend on different things (see the squirt, swerve, and throw effects resource page for a complete summary). I personally think it is important to fully understand the separate effects to be most effective in correcting for them when necessary.

Check out my squirt, swerve, and throw confusion resource page. I think it does a good job of explaining and illustrating the concepts discussed here. Here are some excerpts from the page:

squirt (same as "cue ball deflection"): angular displacement of the cue ball path away from the cue stroking direction caused by the use of English. Squirt increases with the amount of English.

effective squirt: (same as "squerve"): the net effect of squirt and swerve (i.e., the cue ball deflection off the aiming line at object ball impact).

swerve: curve of the cue ball’s path due to cue elevation and English.

Here are two videos that explain and demonstrate all of this fairly well:

NV B.70 - Squirt, swerve, and throw, from VEPS II
NV B.86 - Cut-induced throw (CIT) and spin-induced throw (SIT), from VEPS IV​

Regards,
Dave

 

[ENGLISH!]

permanent resource

Dr. Dave,

Perhaps those diagrams should be PM'd to every member of AZB & an automatic PM to all new members. (or better yet tatooed onto our bridge hand)

I, & I believe Mr. Long, when thinking & 'speaking' from a playing, non-analytical perspective only refer to the final outcome & not all of the intricate parts. When playing, including yourself I believe, we are interested in the total net affect ( result) & not all of the partials that get us there. I know that is simplistic.

I have been playing some very good pool for 46 yrs. while using a form of combined english on almost every shot. I 'knew' nothing about shaft defelction until earlier this year. As you know I must have 'known' about it subconsciously. I did know about 'curve' both 'out & back'.

Vernacular seems to be a problem many times. Mr. Wiley has 'said' throw several times I believe incorrectly but he is trying to catch up but it is very hard sometimes to undo or re-do many years of habit.

I too, wish to say thank you for 'ALL' that you have done to enlighten some of us & for your patience & understanding in our 'resistense' to something contrary to our 'beliefs'.

Thanks again,
Rick

 

[Shaky1]

When we are talking swerve, the ball curves the way it does because we are hitting down on it with spin. If you were able to hit up on it with spin, it would squirt the same direction and curve the same direction that it squirts.
My question is if you were able to hit the cue ball dead level with spin, would it curve at all?

 

[Patrick Johnson]

"azb faq" sticky needed!!

Dr. Dave,

Perhaps those diagrams should be PM'd to every member of AZB & an automatic PM to all new members. (or better yet tatooed onto our bridge hand)

This must be where I'm supposed to insert my usual plea to the AzB Gods to put up a "sticky" thread with an AzB FAQ. The old RSB newsgroup had one and it was very valuable, but now it's homeless - maybe AzB could "adopt" it...?

It would have the answers to all the technical questions that get asked over and over, plus links to major rule sets, etc.

Can I get an "amen"?

pj
chgo

 

[Patrick Johnson]

If you were able to hit up on it with spin, it would squirt the same direction and curve the same direction that it squirts.
My question is if you were able to hit the cue ball dead level with spin, would it curve at all?

Very slightly and only at slowest speed (just before it stops rolling).

pj
chgo

 

[justadub]

This must be where I'm supposed to insert my usual plea to the AzB Gods to put up a "sticky" thread with an AzB FAQ. The old RSB newsgroup had one and it was very valuable, but now it's homeless - maybe AzB could "adopt" it...?

It would have the answers to all the technical questions that get asked over and over, plus links to major rule sets, etc.

Can I get an "amen"?

pj
chgo

Amen. :bow-down:

 

[Patrick Johnson]

Amen. :bow-down:

Tell it, Brother Dub!

The Rev
chgo

 

[dr_dave]

Check out my squirt, swerve, and throw confusion resource page. I think it does a good job of explaining and illustrating the concepts discussed here. Here are some excerpts from the page:

squirt (same as "cue ball deflection"): angular displacement of the cue ball path away from the cue stroking direction caused by the use of English. Squirt increases with the amount of English.

effective squirt: (same as "squerve"): the net effect of squirt and swerve (i.e., the cue ball deflection off the aiming line at object ball impact).

swerve: curve of the cue ball’s path due to cue elevation and English.

Here are two videos that explain and demonstrate all of this fairly well:

NV B.70 - Squirt, swerve, and throw, from VEPS II
NV B.86 - Cut-induced throw (CIT) and spin-induced throw (SIT), from VEPS IV​

Dr. Dave,

Perhaps those diagrams should be PM'd to every member of AZB & an automatic PM to all new members. (or better yet tatooed onto our bridge hand)

I like PJ's idea of an AZB FAQ page. In fact, the reason I created the FAQ resource pages on my website is that such a thing did not exist anywhere else. Although, it is a lot of work to create and maintain a complete, up-to-date, and useful FAQ resource.

I, & I believe Mr. Long, when thinking & 'speaking' from a playing, non-analytical perspective only refer to the final outcome & not all of the intricate parts. When playing, including yourself I believe, we are interested in the total net affect ( result) & not all of the partials that get us there. I know that is simplistic.

You make a good point here. People can learn to compensate for squirt and swerve by just dealing with the combined result of the two effects. However, I still think it is helpful if people understand what is actually going on. IMO, this can speed the learning process at the table and help somebody develop intuition more quickly for knowing how to adjust for all sorts of shots, equipment, and conditions.

Vernacular seems to be a problem many times.

Agreed. That's why I do my best to help people learn standard and appropriate terms and phrases. Without clear and consistent language, communication can involve much confusion and misinterpretation.

I too, wish to say thank you for 'ALL' that you have done to enlighten some of us & for your patience & understanding in our 'resistense' to something contrary to our 'beliefs'.

Thanks Rick. I appreciate it.

Regards,
Dave

 

[dr_dave]

When we are talking swerve, the ball curves the way it does because we are hitting down on it with spin.

Correct!

If you were able to hit up on it with spin, it would squirt the same direction and curve the same direction that it squirts.

Yes. In fact, this is a classic trick shot, where you hit up on a CB sitting on top of a piece of chalk on a rail. Although, the effect isn't very useful in typical play since the cue is usually elevated some to clear the rails.

My question is if you were able to hit the cue ball dead level with spin, would it curve at all?

Excellent question. The answer is no. With a perfectly level cue, the CB would squirt, as normal, but there would be absolutely no swerve. That's why it is important to keep the cue as level as possible, to minimize swerve (unless you need it, for example, with a curve or masse shot).

Regards,
Dave

 

[Shaky1]

Another question. If it would not curve, would the squirt continue off to the side? Meaning would it just keep squirting all the way down the table as if it was on ice? Or kind of like a miscue?

 

[Roger Long]

Why do you think there is a contradiction? The point of NV B.7 is to show that the CB's path does not turn after the CB has begun to roll (even with sidespin), assuming the table is level and the cloth is in good condition and clean (and the ball's weight is balanced).

There is both squirt and swerve in that video, and I did correct my aim for them, but they occur in the first few inches of the shot since the speed is so slow. Squirt occurs immediately off the tip, and swerve occurs only while the CB is sliding (not rolling yet). The amount I had to adjust for the combined effects of squirt and swerve was not very much because for the cue, speed, and cue elevation I was using, swerve cancelled most of the squirt (but I did have to adjust a little as predicted by the FHE method for slow, rolling shots).

I hope that makes sense,
Dave

Basically, we are in agreement. What I've been saying is that a rolling cue ball tends to roll in a straight line, even with english (side spin) applied. That's because the rolling friction isn't great enough to "hold back" on the biased circumferential line caused by the combined forward roll and the english. If the friction was great, there would be a very definite curve (swerve) on every shot with english. I've also said that squirt is greatly reduced when hitting the cue ball above the horizontal centerline. This is also due to reduced cloth-to-ball friction because of it being rolling friction.

Here's where we differ a bit: You said swerve was present in your video; it was just in the first few inches. I've viewed that video over and over, and I can't see any swerve at all. I have also set that shot up on various pool tables many times myself, and I have never been able to see any swerve or squirt as long as I hit the ball above center with a "level" cue and a soft-to-medium stroke (you know, the kind we use on 90% of our pool shots).

My feeling is still the same as before: Hitting above the centerline with a level cue starts the ball off rolling (It can't do anything else but that, can it?), which essentially makes squirt and swerve non-factors. And even if there is a slight amount of squirt and swerve present (despite my not being able to see them), one is almost entirely canceling the other out.

As I said before, I believe cue ball deflection (squirt) has been over emphasized. It is primarily a marketing tool used to sell LD shafts. And it's been very successful at it, too! :grin-square:

Roger

 

[dr_dave]

Another question. If it would not curve, would the squirt continue off to the side?

The CB would continue in a straight line immediately off the tip in the squirt direction. There would be no swerve to bring the CB back toward the aiming line (or across it, if the cue were elevated). So as the CB travels, the distance between the line of the CB and the initial aiming line continues to grow.

Regards,
Dave

 

[Shaky1]

Thanks Dave!

 

[dr_dave]

Basically, we are in agreement. What I've been saying is that a rolling cue ball tends to roll in a straight line, even with english (side spin) applied.

That's correct.

Here's where we differ a bit: You said swerve was present in your video; it was just in the first few inches. I've viewed that video over and over, and I can't see any swerve at all.

At slow speeds, the swerve happens almost immediately ... much too quickly to see in the video or even at the table.

I have also set that shot up on various pool tables many times myself, and I have never been able to see any swerve or squirt as long as I hit the ball above center with a "level" cue and a soft-to-medium stroke (you know, the kind we use on 90% of our pool shots).

The amount of squirt depends on the particular shaft. If you try the same shot with different shafts, there will be different amounts of squirt. The swerve depends on conditions, shot speed, and exact cue elevation. Results will vary with these things.

Now, if your cue elevation were just the right amount to have the swerve exactly offset the squirt (for a given cue, shot speed, and conditions), it is possible for the swerve to exactly cancel the squirt, resulting in the CB heading exactly in the aiming-line direction (i.e., parallel to the line of the cue). In this case, you might not think there is squirt or swerve, but that is not the case. There is always both with sidespin and a non-level cue. The cue is almost never level at a pool table because the cue (and you grip hand) must clear over the rails. Sometimes squirt and swerve can cancel, and they often happen too quickly to see, but the effects are real.

My feeling is still the same as before: Hitting above the centerline with a level cue starts the ball off rolling (It can't do anything else but that, can it?), which essentially makes squirt and swerve non-factors. And even if there is a slight amount of squirt and swerve present (despite my not being able to see them), one is almost entirely canceling the other out.

With a perfectly level cue, it is possible to roll the CB with sidespin immediately off the tip. However, with an elevated cue, there is some sliding (due to the masse spin) before complete roll occurs. With more cue elevation and more shot speed, this effect is exaggerated. However, even with only slight cue elevation and slow speeds, the same effects are still there, they are just much smaller and happen too quickly to notice. Regardless, the only time squirt/swerve is a "non factor" is when the swerve (for a given cue elevation, shot speed, and cloth/ball conditions) exactly cancels the squirt (for a given cue). The shot speed must also be slow enough so there is no appreciable shift in the line of the CB while CB roll develops (while the swerve occurs).

As I said before, I believe cue ball deflection (squirt) has been over emphasized. It is primarily a marketing tool used to sell LD shafts. And it's been very successful at it, too! :grin-square:

I think there is some truth in this. Although, I also think (and know) that if one cannot adjust for squirt/swerve effects (either consciously or subconsciously), one will not be able to play pool at a top level.

Regards,
Dave

 

[ENGLISH!]

I do not mean to impose on the converstion but I just wanted to throw in, if the english is being applied with a slight back hand pivot that would...what word, offset, diminish the 'overall net result'. Just a thought but I'm sure that has been asked & answered. Just trying to clarify & make sure the converstion is on the same plane.

Sorry for the intrusion.
Rick

 

[Roger Long]

I do not mean to impose on the converstion but I just wanted to throw in, if the english is being applied with a slight back hand pivot that would...what word, offset, diminish the 'overall net result'. Just a thought but I'm sure that has been asked & answered. Just trying to clarify & make sure the converstion is on the same plane.

Sorry for the intrusion.
Rick

That's a good question, Rick, and one I'd like to get back to very soon. First, I'd like to have a little more discussion with Dr. Dave on sliding-vs-rolling balls.

Roger

 

[CJ Wiley]

"play with a center ball and/or level cue" is a recipe for a LOT of missed shots.

You didn't have to worry about it, CJ, because it wasn't as big a factor as it has been made out to be since the introduction of "low-deflection" shafts. Swerve wasn't a factor because you, and all other good players, knew how to curve (swerve) the cue ball by elevating the butt end of the cue and applying english. No fancy shaft needed. But here's the part where I'm sure to catch some flak: I believe that squirt, along with curve, is almost non-existent whenever the cue ball is struck above the horizontal center line with a level cue, even when english is applied. And isn't a rolling cue ball used most often when propelling it around the table?

The marketing of low-deflection shafts is what put, and keeps, worry in players' minds. Tests hitting the cue ball with english right on the horizontal center line (which is the exact point where squirt is maximized) have shown that some shafts do indeed produce less squirt than others. However, no shaft totally eliminates squirt, and, as I've already stated, squirt and swerve are essentially non-factors when you stay above the horizontal center line, regardless of what kind of shaft you use.

Roger

I never did the "scientific/video" experinents, but I have tried using a perfectly level cue and found out that was NO GOOD to play with....I play best with my cue at a certain angle going towards the bottom of the cue ball (I'm not certain what angle that is, I've never measured it :wink...the suggestions "play with a center ball and/or level cue" is a recipe for a LOT of missed shots.

 

[Living Legend]

wrong thread .....

 

[LAMas]

I do not mean to impose on the converstion but I just wanted to throw in, if the english is being applied with a slight back hand pivot that would...what word, offset, diminish the 'overall net result'. Just a thought but I'm sure that has been asked & answered. Just trying to clarify & make sure the converstion is on the same plane.

Sorry for the intrusion.
Rick

Is there a difference between applying BHE or FHE after one has lined up for a center of the CB hit and shifting the cue parallel to the side of the center of the CB - the angle of attack would be different.

I can use a bit of english and send the CB straight into the center diamond on the head rail with the CB in the center of the table and the CB will leave the rail at a slight angle to the same side due to the english applied.

If this is correct, then when CJ uses a "bit" of inside english on the CB to cut the OB with squirt - what is happening? Is the CB hitting the OB a bit thinner with no appearant english imparted to the OB or both?

Question for CJ, do you use BHE, FHE or both or parallel shifting of the cue?

Thanks.